Advice for fluid simulation

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Old 01 January 2013   #1
Advice for fluid simulation

Hello,

I have a client who wishes to create the effect of water filling up a container. In this case it will be from the bottom (like a plug hole that is acting like a tap pushing the water up into the container) as opposed to the typical - pouring in from the top.

I haven't got any experience with maya fluid simulations but was wondering if somebody could point me in the right direction for a good tutorial that would enable me to adjust what I learn in the lesson to get what I want.

Also I need to turn it round in one day, do you think this is realistic?

Thanks for any help on this.

Spencer
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Spencer Carpenter
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www.spencercarpenter.co.uk
spencer@spencercarpenter.co.uk
 
Old 01 January 2013   #2
Originally Posted by Snape: Also I need to turn it round in one day, do you think this is realistic?


not really, especially since you have never done this before?
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Old 01 January 2013   #3
Well I have got time to research the techniques before I work on the project. Also I think the simulation will at it simplest be a cylindrical container filling which I would hope wouldn't cause too many variables to go wrong...
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Old 01 January 2013   #4
Use the water preset for nParticles and head to the liquid settings on particleShape1 node, make sure tension attribute is turned on and up. HAve a look at the help docs for more info on the atributes, normally the defaults are a good start. To mesh your particles go to the modify menu and convert nParticles to polygons, this will activate the meshing attributes on the nPArticleShape1, it will take a while to tweak and get the best look but you will never get it perfect or looking right. The biggest problem I believe is the amount of particles required to produce a decent sim and Mayas inability to handle large particle numbers. Really at the end of the day if you want something looking realistic you have to go Realflow, if you dont mind a sim looking just okay then Maya will suit your needs. Looking at your requirements might be okay for Maya since I cant see many splashes or spillages occurring but then just having water fill a cup evenly isnt really exciting stuff.

Anyway thats my experience.
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Old 01 January 2013   #5
also take a look at the soup peak and smooth deformers, I haven't tried it, but the example movie looks like it could improve the results
 
Old 01 January 2013   #6
Thanks Guys Ill check that out.

To be more specific my client wants me to fill a stadium model with water.

It's ok to have a sim look about it though I would like it to be an impressive sim. I was thinking I'd just do it inside a cylinder then put the stadium model over it or maybe a low res stadium with very basic deflection objects to represent the stands etc.

So you think it's not worth using the fluid sim then? I thought it might be a bit more 'automatic' than particles once I've got some basic constant settings for the fluid...

Thanks again for any advice here it's really appreciated.

Spencer
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Old 01 January 2013   #7
Yep SOuP nodes help improve mesh look. The peak node is a deformer values around -1 are good start.

Honestly using Maya for this type of efect is more trouble than what its worth - its hard to get volume without particles flying away from each other not to mention pesky pairs of particles taking off, if you can get a copy of Realflow then you'll get more bang for your effort and faster too.
If you really have to use MAya then aim for at least a million particles - should work for filling up a glass as you mentioned - a stadium well require a lot more. With those high numbers though you could be waiting all day for a 100 frame sim.
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Last edited by Aikiman : 01 January 2013 at 02:57 AM.
 
Old 01 January 2013   #8
For what you are trying to achieve I have to agree with what has been said. I personally wouldn't go near Maya to do this. This sounds like a job for Realflow and possibly using the Hybrido system.

Good luck in any case.
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Old 01 January 2013   #9
Thanks for your advice my only issue is that real flow is very expensive.

Am I right in thinking that the work flow is:

1) in realflow, import a mesh to act as fluid deflectors in the scene
2) simulate in real flow
3) export an animated mesh back into maya and then add shaders

I have seen that you can rent real flow per week but I'm still worried that it adds budget which isn't there and causes round tripping which if doesn't go smoothly will cost lots of time...
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Old 01 January 2013   #10
a stadium sounds like a totally different assignment than a cylinder. i understand you might not be able to say much more, but getting a good sim is a large job, probably even with real flow. Just to fill a stadium would require a higher inflow than outflow, and a stadium usually has large exits. And to fill it quickly enough to make it look visually interesting would require an extreme inflow of water. I assume we are talking geisers or something similar, it sounds like something from a catastrophe movie. A very important part of getting it visually intetesting would be showing the great forces the water creates, breaking, lifting things. Admittedly I have not understood the intended use, making it good enough for a cartoon is something very different from making it look real. If you would end up using maya I would really try to create the clips required, and not a general sim to get clips from.
 
Old 01 January 2013   #11
Originally Posted by Snape: Thanks for your advice my only issue is that real flow is very expensive.

Am I right in thinking that the work flow is:

1) in realflow, import a mesh to act as fluid deflectors in the scene
2) simulate in real flow
3) export an animated mesh back into maya and then add shaders

I have seen that you can rent real flow per week but I'm still worried that it adds budget which isn't there and causes round tripping which if doesn't go smoothly will cost lots of time...


Ok. Before you commit to the job for your client consider that, even with Realflow, what you are trying to do probably requires more experience with Realfow than you actually have (which appears to be none). Yes, fluid simulations are expensive in both time and money. If your client really wants a stadium filling up with fluid - then that it is going to be expensive in both time and money.

If you think you can get by with Maya then I am afraid you are going to have a hellish time. Watch this video to get an idea of how badly things can go wrong with Maya fluids. Realflow is hundreds of times better and easier but still not easy.
http://www.youtube.com/watch?v=hlXba2t763Y

Don't fall out with a client by promising something you might not be able to do. You don't want to get a bad reputation.

All the best
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I think it was Francis Bacon that said there is 'no such thing as an original thought.' But I suspect he was quoting someone else.
 
Old 01 January 2013   #12
Originally Posted by tobbew: a stadium sounds like a totally different assignment than a cylinder. i understand you might not be able to say much more, but getting a good sim is a large job, probably even with real flow. Just to fill a stadium would require a higher inflow than outflow, and a stadium usually has large exits. And to fill it quickly enough to make it look visually interesting would require an extreme inflow of water. I assume we are talking geisers or something similar, it sounds like something from a catastrophe movie. A very important part of getting it visually intetesting would be showing the great forces the water creates, breaking, lifting things. Admittedly I have not understood the intended use, making it good enough for a cartoon is something very different from making it look real. If you would end up using maya I would really try to create the clips required, and not a general sim to get clips from.


Hi Tobbew,

I can't be too specific as I've had to sign an NDC but it really doesn't need to be high end feature film style. More just something which which would be much more impressive than trying to simulate the effect without some sort of dynamics.

There will be no exits in the stadium and it's more of an illustration if that helps to gauge the intended look.

Thanks again.

Spencer
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Spencer Carpenter
Freelance 3D Artist
www.spencercarpenter.co.uk
spencer@spencercarpenter.co.uk
 
Old 01 January 2013   #13
Originally Posted by bellwether: Ok. Before you commit to the job for your client consider that, even with Realflow, what you are trying to do probably requires more experience with Realfow than you actually have (which appears to be none). Yes, fluid simulations are expensive in both time and money. If your client really wants a stadium filling up with fluid - then that it is going to be expensive in both time and money.

If you think you can get by with Maya then I am afraid you are going to have a hellish time. Watch this video to get an idea of how badly things can go wrong with Maya fluids. Realflow is hundreds of times better and easier but still not easy.
http://www.youtube.com/watch?v=hlXba2t763Y

Don't fall out with a client by promising something you might not be able to do. You don't want to get a bad reputation.

All the best


Thanks for the advice, I have found a tutorial online that helps but doesn't quite explain everything.

Your right not to promise something I can't deliver. Luckily I have a bit of time to practise first before monday next week.

Having played around a little I can get a very basic simulation looking ok. I can't work out how to more than about a 5th of the container to fill though. It's really helped watching that video it give a brilliant steer what to watch out for.

Does anybody know of any thorough tuts online, even ones that need to be paid for?

Thanks

Spencer
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Spencer Carpenter
Freelance 3D Artist
www.spencercarpenter.co.uk
spencer@spencercarpenter.co.uk
 
Old 01 January 2013   #14
Not sure how I didn't see this before but this looks pretty good...

http://www.thegnomonworkshop.com/st...cs#.UPcYj6FaZAM
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Spencer Carpenter
Freelance 3D Artist
www.spencercarpenter.co.uk
spencer@spencercarpenter.co.uk
 
Old 01 January 2013   #15
Once you've watched that DVD then go over to NextLimit and their forums, Im sure Ive watched some handy youtube vids on hybrido. These with a few weeks practice should be enough to do your effect, dont expect closeup shots.

Good luck
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